Wetting current

[2] A thin film of oxidation, or an otherwise passivated layer, tends to form in most environments, particularly those with high humidity, and, along with surface roughness, contributes to the contact resistance at an interface.[3] Providing a sufficient amount of wetting current is a crucial step in designing circuits that use switches with low contact pressure.Failing to do this might result in switches remaining electrically "open" when pressed, due to contact oxidation.[7][8] Carbon brushes develop high resistance glaze when they're used without current flow for an extended period.A special circuit is utilized for turbines and generators to introduce current through the brushes into the shaft to prevent this contact fritting.
frettingelectrowettingelectrical and electronics engineeringelectric currenthumiditycontact resistancecircuitsswitchescapacitorsplicesG.992.3LinecardContact cleanerCohererContact protectionElectromigrationMcGraw HillTyco Electronics CorporationDesign NewsBellcoreoxidationline splicesline cardssubscriber loop cabinetCRC PressTaylor & Francis, Inc.Holm, RagnarHolm, ElseSpringer Science & Business MediaSpringer-VerlagSchweitzer Engineering Laboratories, Inc.Teradyne, Inc.